A decoloring apparatus decolors an image formed on a sheet so that the sheet can be reused. The decoloring apparatus reads the sheet after decoloring, and determines whether or not the image formed on the sheet has been effectively decolored.
When a sheet is transported while it is skewed at a time the sheet is read to determine decoloring of an image formed on the sheet, there is a concern that the decoloring apparatus may make an error when determining the effectiveness of the decoloring.